1. Field of the Invention
The present invention relates to a supporting mechanism of a slide door supported to a cab of a construction machine, for example, a hydraulic shovel, a crane vehicle or the like, and particularly relates to a supporting mechanism of a slide door which can be smoothly opened and closed even in the case that a great load is locally applied to a slide door surface at a time of being opened and closed.
2. Description of the Related Art
In recent construction machines, for example, as disclosed in the publication of Japanese Utility Model No. 2526932, a cab placed on a revolving deck on a wheel-type or track-type travel unit or the like is made compact so as to be accommodated in a moving track thereof, avoiding an interference with an implement at a time of working. Further, in order to secure safety, comfortableness and an effective space at a time of rotating the revolving deck, the structure is made such that an entrance and exit of the cab is opened and closed by a slide door, an outer side surface portion including the slide door is placed within a circular arc surface having a radius of curvature close to a maximum swing radius of the revolving deck and the slide door is formed in the same circular arc surface shape as the outer side surface portion, thereby being slid along the circular arc surface.
A window is provided on a whole surface of a front surface portion of the cab, particularly the field of view of the front upper portion is made wider through the front surface window portion so as to improve an operability, and in order to avoid the interference with the implement such as a bucket, a boom or the like, the upper side of the front surface portion is formed in a rearward inclined shape so that the upper side is positioned toward the rear portion.
In this case, in a structure in which pillars stood from four corners of the cab vertically stand in parallel with each other, even when an outer side surface of the cab is formed in a circular arc shape along an outer diameter of the revolving deck as mentioned above, it is possible to form the pillar in the same thickness all along its vertical direction. However, in the case that the upper portion of the front surface window portion of the cab is formed in a rearward inclined shape as mentioned above, when the outer side surface portion is formed in a single circular arc portion, that is, a part of a cylinder body, in the front pillar stood between the front surface window portion and the outer side surface portion so as to be vertical in a front view, a lateral width in a side view is gradually increased in correspondence to an angle of incline of the front surface window portion from an incline starting point of the front surface window portion to an upper end, thereby significantly reducing the field of view of the outer front upper portion of the cab. Accordingly, for example, in the publication of Japanese Utility Model No. 2526933, a substantially whole surface of the outer side surface is inward inclined toward the upper portion, and the lateral width of the front pillar in the front view is made uniform, whereby the machine body is totally balanced.
Further, an upper slide mechanism of the slide door disclosed in the publication mentioned above is structured such that a first rail horizontally extending in a longitudinal direction is mounted to a lower end of a supporting bracket suspended from a hood of the cab, a first roller mounted to an upper inner surface in a front end side of the slide door is rolled on the first rail, a second rail having an inverted U cross sectional shape is provided on an outer side surface of the supporting bracket, and a second roller mounted to an upper inner surface in a rear end side of the slide door is loosely fitted to the second rail from below, thereby being guided and rolled around a vertical axis. On the contrary, a lower slide mechanism of the slide door is structured such that third and fourth rollers mounted to front and rear portions of the inner surface of a lower end portion of the slide door are loosely fitted to a third rail provided along a lower end edge of the cab and having an inverted U cross sectional shape from below, whereby the third and fourth rollers at front and rear portions are respectively guided and rolled around the vertical axis.
Further, for example, in the cab disclosed in the publication of Japanese Patent No. 2722055, a curvature of a front half portion of the outer side surface portion of the cab is set to the same radius of curvature vertically, the structure is formed in a three dimensional curved surface obtained by moving a center point of circular arc rearward as moving upward so that all the circular arcs cross at a boundary line between the front half portion and a rear half portion in the outer side surface portion, and the structure is made such that a width in the side surface side of the pillar does not change in a vertical direction, thereby securing the field of view of the outer front surface upper portion of the cab.
In this publication, a door slide surface in a door opening portion of the cab is defined by a lower circular arc having the same center as a rotational center of the revolving deck from a lower end of the pillar in a lower end of the door opening portion and brought into contact with a position having a maximum cab width from the lower end of the door opening portion, an outer lower end of a rear end surface of the dab is formed by a basic circular arc connecting a point positioned inside the revolving deck with respect to a crossing point between the rear end surface and the lower circular arc to the lower end of the door opening portion, and a portion between the lower end of the door opening portion and the upper end of the door opening portion is defined by the same circular arc obtained by shifting the center of the basic circular arc rearward in correspondence to a rearward inclination of the front window portion. Then, the outer side surface disposed at the rear of the door opening portion and reaching the rear end of the cab is formed as the same cylinder surface comprising the basic circular arc connecting between the rear end of the door opening portion and the rear end of the cab.
In accordance with the structure mentioned above, in the cab for the construction machine disclosed in the publications mentioned above, even when the front surface window portion of the cab is formed so as to have the same width vertically and the upper portion thereof is inclined rearward, an appearance viewed from the front portion of the cab is excellent while the cab width is made maximum, it is easy to produce the structure, and the door stopper provided at the rear end of the cab is not protruded from the revolving deck.
However, in accordance with the cab for the construction machine disclosed in the publications mentioned above, the door opening portion in the outer side surface portion of the cab is formed in the three dimensional curved surface as mentioned above, and the rear outer side surface portion between the rear end of the door opening potion and the rear end of the cab is formed in the cylinder surface. The three dimensional curved surface of the door opening portion and the cylinder surface of the rear outer side surface portion are formed in the shape along the basic circular arc having the same radius in the plan view as mentioned above, however, for example, the three dimensional curved surface side in the upper end of the door opening portion is formed in a shape along the circular arc obtained by moving the center point thereof from the center of the cylinder surface of the rear outer side surface portion to the rear portion.
In this case, the basic circular arc in the lower end of the door opening portion is in inward contact with the lower circular arc passing through the lower end of the front outer side pillar. Accordingly, if the cylinder surface of the rear outer side surface portion is, for example, in the cylindrical shape along the lower circular arc, the three dimensional curved surface and the cylinder surface of the rear outer side surface portion can be formed in a shape of being smoothly connected with the inner contact point as the boundary by rearward moving the center point in correspondence to each of height positions on the outer side edge of the front window portion and subsequently calculating the circular arc being inward contact with the lower circular arc at the rear end so as to form the three dimensional curved surface.
However, in any cases, it is necessary that the whole shape of the slide door mentioned above is provided with the same configuration along the outer side surface portion of the cab having the three dimensional curved surface in at least a part thereof, as mentioned above. Further, the slide mechanism of the slide door is structured such that a guide track of the rail arranged in the upper and lower end edge portions of the outer side surface portion of the cab or in the center portion is generally formed in a curved line along the longitudinal direction of the outer side surface portion, as well as the slide door disclosed in the publication of Japanese Utility Model mentioned above. Accordingly, when opening and closing the slide door, in particular, when opening an opening portion of an access port for passenger by the slide door, the inner surface of the three dimensional curved surface portion rides over the rear outer side surface portion of the cab via an intermediate pillar, whereby the whole of the door is necessarily lifted up outwardly from the rear outer side surface portion.
As a result, it is necessary to set the placing position of the cab placed in the revolving deck mentioned above to a position obtained by moving the outer side surface portion of the cab toward the center side from the circular arc of the radius of swing of the revolving deck by the lifted-up amount of the slide door, causing to narrow a interior volume of the cab. Further, particularly at a time of opening the slide door, an excessive force is applied to a part of the door when the door rides over the rear outer side surface portion of the cab, whereby there may be a case that a problem to the door opening operation is generated. In order to deal with the matter and in order to make it easy to make the inner surface of the three dimensional curved surface portion ride over the rear outer side surface portion of the cab, the structure can be made such that the supporting mechanism of the door provided between the door and the cab, particularly, a portion between the rail portion and the rolling roller has a margin so as to expand a gap between the door and the cab. However, in the structure mentioned above, there is necessarily generated a portion which is largely shaky locally on the slide track of the door between the door and the cab, so that there is a risk that a function as the door is lost due to the influence of wobbling even when the door is closed.
The present invention is made so as to solve the problems mentioned above, and a particular object thereof is to provide a supporting mechanism of a slide door in which a lower end rail portion which is most easily get dirty in a slide door opening and closing portion does not get dirty and an operation can be smoothly and without being shaky can be performed even when a great load is locally applied to the slide door at a time of operating the slide door.
The object mentioned above can be effectively achieved by the present invention.
In accordance with the invention, there is provided a supporting mechanism of a slide door placed in an entrance/exit comprising: upper and lower rails extending along edge portions of upper and lower ends of the entrance/exit; and guide rollers respectively provided at least in upper and lower end portions of a front edge of the slide door. In this mechanism, the lower rail is constituted by one narrow plate rail having a lower end edge being a free end, the lower guide rollers include a set of two or more rolling rollers, and the set of two or more rolling rollers hold and support the lower rail therebetween from below so as to freely roll.
For example, since the lower rail is suspended downward from a floor surface of the entrance, it is hard that dusts and earth and sands are stored in the rail, so that the guide rollers maintain a smooth rolling property after a long time use. Further, since the lower guide rollers roll along the rail while holding the lower rail therebetween, the lower guide rollers can smoothly roll without being shaky along the entrance, for example, even when a little excessive force is applied to a lower end of the door, so that there would be no gap between the door and the entrance and exit.
Preferably, the upper rail includes a first rail having a free end at a lower end edge thereof; and a second rail substantially horizontally extending toward an outer side, and the upper guide rollers are constituted by first rolling rollers composed of a set of two or more rollers having a substantially vertical rolling axis, and a second rolling roller having a substantially horizontal rolling axis, and the first rolling rollers of the set of two or more rollers are gripped and supported with respect to the first rail from below, and the second guide roller is supported and guided to an upper surface of the second rail so as to roll.
In accordance with the present invention, in addition to the supporting mechanism of the lower end portion of the front edge in the slide door, the supporting mechanism of the upper end portion of the front edge is defined. In accordance with the supporting mechanism of the upper end portion of the front edge, since a main weight of the slide door is supported by the second rail in the room side, it is possible to sufficiently support the slide door by the supporting mechanism of the lower end portion of the front edge as mentioned above, and further since the first guide roller is gripped and supported by the first rail from below in the same manner as that of the supporting mechanism of the lower end portion of the front edge, it is possible to prevent the door upper end portion from being shaky.
Further preferably, each of the guide rollers is formed in a drum shape. In accordance with the guide rollers having the configuration as above, for example, even when a load is applied to each of the guide rollers from various directions and the supporting axis thereof is elastically deformed and the rolling surface of the guide roller moves in a direction of the supporting axis, the rolling portion of the guide roller brought into contact with the rail is always in point contact, so that it is possible to always secure a smooth rolling at a small friction resistance.
Still further preferably, the supporting portion of each of the guide rollers having the substantially vertical rolling axis can rotate around the vertical axis. In accordance with the structure mentioned above, the guide roller can be easily guided along the rail drawing the curved track in a further smooth manner.